Steerable angioplasty device

ABSTRACT

An elongate steerable implement is disclosed, which may be either a steerable guidewire or catheter for coronary angioplasty applications. A floppy steerable tip on a steering region at the distal end of the implement and a control device at the proximal end are connected by means of a plurality of axially movable deflection wires extending throughout the implement. Manipulation of the control permits deflection of the steering region throughout a full 360° range of motion about the axis of the implement, without axial rotation or &#34;torquing&#34; thereof.

This application is a continuation of application Ser. No. 489,706,filed Mar. 7, 1990, now abandoned which is a continuation of Ser. No.295,124, filed Jan. 9, 1989, now U.S. Pat. No. 4,921,482.

BACKGROUND OF THE INVENTION

The present invention relates to steering devices such as may be usedwith catheters, cannulae, guidewires and the like. More particularly,the present invention relates to catheters and guidewires that aresteerable through body lumen or cavities and positionable within oraimable at obstructions, organs, or tissue within the body from aposition external to the body.

Medical catheters generally comprise elongate tube-like members whichmay be inserted into the body, either percutaneously or via a bodyorifice, for any of a wide variety of diagnostic and therapeuticpurposes. Such medical applications frequently require use of a catheterhaving the ability to negotiate twists and turns, particularly withregard to certain cardiovascular applications.

One such application, Percutaneous Transluminal Coronary Angioplasty(balloon angioplasty), requires manipulation of a catheter from aposition outside the patient's body through extended portions of thepatient's arterial system to the stenotic site for the purpose ofalleviating the obstruction by inflating a balloon. This particularprocedure has been performed with increasing frequency over the pastyears in preference to open heart bypass surgery, when possible.

In a typical angioplasty procedure, a guidewire is transluminallyinserted into the brachial or the femoral artery, to be positionedwithin the stenotic region and followed by a balloon catheter. Thecardiologist usually prebends the distal tip of the guidewire beforeinsertion and then rotates (or torques) the wire once it has reached abranch artery to enable the guidewire to enter the branch. If the angleof the bend has to be adjusted, the guidewire must be removed, re-bentand reinserted, sometimes several times. Particular difficulty isencountered with prebending where an artery branches at one angle, andthen sub-branches at a different angle. This procedure is attended bythe risk of significant trauma to the arterial lining, and, in manycases, the obstruction cannot be reached at all with the guidewire andcatheter.

Coronary arteries are tortuous, have many sub-branches and often theobstruction is either located where the diameter of the artery is smallor, by its very presence, the obstruction leaves only a very smallopening through which a guidewire and/or catheter can be passed.Consequently, the cardiologist often finds it very difficult to maneuverthe guidewire or catheter, which are typically several feet long, fromthe proximal end.

Steering the prebended guidewire is further complicated by the fact thatbranches project at all different radial angles, thus necessitatingrotation of the guidewire to the appropriate degree to enter the desiredarterial branch. However, rotation of the distal end of the wiretypically lags behind rotation of the proximal, control end, so thatprecise rotational control is not possible. Also, friction in thearteries can cause the distal end to rotate in a jerky fashion which cantraumatize the vascular intima.

In another application, Transluminal Laser Catheter Angioplasty (laserangioplasty), the delivery of laser energy from an external source to anintraluminal site to remove plaque or thrombus obstructions in vesselsis accomplished by providing a waveguide such as a fiber optic bundlewithin a catheter. The nature of laser angioplasty requires an evengreater ability to precisely manipulate the catheter, to control and aimthe laser light at the specific plaques or thrombi to be removed.

A variety of attempts have been made in the past to provide catheterswhich are steerable from the proximal end to enable the catheter to beaimed or advanced through nonlinear body cavities. For example, U.S.Pat. No. 4,723,936 to Buchbinder, et al. discloses a balloon catheter,which is said to be steerable from the proximal end. The catheter isprovided with a deflection wire going along the entire length of thecatheter, which may be axially displaced to cause deflection at thedistal end. However, the tip of the catheter can be bent in onedirection only, and the entire catheter must be rotated or torqued to beguided. In addition, the design requires a relatively large diameterdeflection wire, which precludes extremely thin diameter catheters, suchas those preferred for use for laser or balloon angioplastyapplications.

U.S. Pat. No. 3,470,876 to Barchilon discloses a catheter device havinga central lumen extending therethrough, and four tensioning cordsextending along an inner wall of the catheter. The '876 patentspecifically recites that catheters may be produced in accordance withthe Barchilon design having diameters of 0.125 to 2 inches, and aresuited for applications such as within the duodenal bulb or ascendingcolon. These diameters are unsuited for use as a guidewire in coronaryangioplasty, which typically requires diameters in the area of as smallas from about 0.014 to 0.018 inches.

In the context of coronary angioplasty applications, the prior artgenerally suffers from disadvantages such as limited steerability andexcessive external diameters. Limited catheter tip steerability resultsin greater time spent in the body and significantly elevated risk oftrauma both to the vascular intima and to the patient in general.Multiple insertions of guidewires or catheters may lead to thrombosis,as a result of coagulation commencing along a guidewire surface.Additionally, precise directional control in laser angioplasty is of theutmost importance to assure accurate aiming of the laser beam to ablatethe attendant plaque. However, the only prior art catheters havingmulti-directional steerability are typically greatly in excess ofpractical angioplasty catheter diameters.

Thus, there remains a need for a small diameter steering device, whichmay be readily adapted for use in the construction of either guidewiresor catheters, and which is especially suited for procedures such asballoon or laser angioplasty. Preferably, the steering device isconstructed in a manner which permits a diameter as small as that ofexisting dilatation catheters or guidewires used in angioplastyapplications, yet is capable of complete deflective movement, throughouta full 360° range of motion, without axial rotation.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided an improved steerable guidewire or catheter implement of thetype useful for percutaneous transluminal insertion into the coronaryvascular system. The invention permits controlled negotiation ofbranches and turns to guide an angioplasty catheter or guidewire to anarterial stenosis or lesion or other treatment site without the need forprebending or torquing of the instrument. The distal tip on steerableimplements made in accordance with the present invention can becontrollably radially displaced in any direction, thus permitting a full360° range of motion without the need to rotate the body of thesteerable implement.

In one embodiment of the present invention, a guidewire is providedhaving an elongate flexible shaft with a central lumen extendingtherethrough and a floppy resilient tip on the distal end. An axiallyextending steering post is disposed within a steering region on thedistal portion of the flexible shaft. The steering post is pivotablysecured at its proximal end to a radial support axially secured withinthe flexible shaft at the proximal end of the steering region, toprevent axial displacement of the steering post while at the same timepermitting lateral deflection of the steering post out of parallel withthe axis of the flexible shaft.

At least one and preferably four deflection wires are axially movablydisposed within the lumen of the flexible shaft, and extend proximallyfrom distal point of attachment on the steering post throughout thelength of the flexible shaft to a control at the proximal end thereof.Each deflection wire passes through a notch or orifice on the radialsupport.

Axial movement of any one of the deflection wires in a proximaldirection displaces the axis of the steering post in a unique lateraldirection, and through combinations of proximal axial displacement ofmore than two deflection wires, the steering post is caused to deflectlaterally and rotate throughout a full 360° range of motion about theaxis of the flexible shaft.

The steerable angioplasty device of the present invention can thusnegotiate tortuous and branched arterial systems, without the need forwithdrawal and multiple insertions to deflect the tip, or axial rotationof the catheter body. The steerable angioplasty device can be readilymanufactured in accordance with known techniques, and at a low per unitcost.

These and other features and advantages of the present invention willbecome apparent from the detailed description of preferred embodimentswhich follows, when considered together with the attached drawings andclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional perspective view of a steerable guidewireaccording to the present invention, with the outer tubular casingremoved.

FIG. 2 is an elevational sectional view of the guidewire of FIG. 1,illustrated in a first deflected position.

FIG. 3 is an elevational sectional view of the guidewire of FIG. 1,illustrated in a second deflected position.

FIG. 4 is a partial sectional perspective view of a steerable laserangioplasty catheter according to the present invention.

FIG. 5 is a further embodiment of the steerable guidewire of the presentinvention.

FIG. 6 is a schematic view of the guidewire of FIG. 1, illustrated asnegotiating an arterial branch point and approaching an arterialstenosis.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, there is disclosed an elongate flexible implement10, having a tubular body with a proximal end 12 and a distal end 14.The distal end 14 comprises a steering region 16, and the proximal end12 is provided with a control 18 for steering the implement 10, whichmay be, for example, a steerable guidewire or catheter. Although thesteering device of the present invention will generally be describedherein as incorporated into an angioplasty guidewire, it is to beunderstood that one skilled in the art will be able to readily adapt thesteering device to other medical and nonmedical applications.

The body 11 of steerable implement 10 may be any desired length frominches to many feet depending upon the intended application. In anembodiment useful as an angioplasty guidewire or catheter, the body 11will typically be several feet long, and will preferably be about 180cm, as is typical of existing angioplasty catheters. However, anysuitable length may be used.

The body 11 may be constructed in any of a variety of ways known in theart, such as by tightly winding a coil of metal wire, or extrusion of arelatively flexible biocompatible polymer such as polyethylene. Woundguidewires preferably comprise a high tensile strength wire of aresilient, noncorrosive metal such as stainless steel or platinum, andmay have a circular cross-section with a diameter of from about 0.001 to0.020 in. The wire may alternatively have a rectangular cross-section offrom about 0.001 to 0.020 inches by from about 0.001 to 0.040 inches, orother variations known in the art. Construction materials and techniquesfor manufacturing wire wound guidewires are well known in the art, and atypical 180 cm teflon coated 0.014 inch or 0.016 inch diameternonsteerable guidewire may be obtained from U.S. Catheter, Inc., adivision of C. R. Baid, Inc., located in Billeriea, Massachusetts,U.S.A.

The external diameter of wire wound guidewires will of course be afunction of the intended application. The wire wound coronaryangioplasty guidewires incorporating the steering device of the presentinvention are preferably wound to have an external diameter in the rangeof from about 0.014 inches to about 0.018 inches. In steerable catheterapplications, the diameter of the catheter can be varied to optimize thediameter of a central working channel as desired, while stillmaintaining a sufficiently small exterior diameter for the intendedapplication. Steerable balloon angioplasty catheters incorporating thepresent invention will typically have an exterior diameter in the rangeof from about 0.020 inches to about 0.041 inches or larger as permittedby location of the lesion.

Preferably, the exterior surface of the wound coil type guidewire shaft10 is provided with an elastic, biocompatible coating or sheath toprovide a smooth outer surface. Suitable coatings can be formed bydipping, spraying or wrapping and heat curing operations as are known inthe art. Alternatively, heat shrinkable tubing can provide a suitableouter sheath. A coating material should be selected which will permitsufficient flexing of the body without cracking, will minimize slidingfriction of the implement 10 during insertion and removal, and issubstantially chemically inert in the in vivo vascular environment. Avariety of suitable materials are known, including, for example,polytetrafluoroethylene, urethane or polyethylene.

The body of flexible implement 10 typically terminates at its distal end14 in a closed tip 20. Numerous guidewire and catheter tip constructionsare known in the art and need not be detailed extensively herein. Ingeneral, the tip 20 is preferably a rounded closure constructed of aresilient polymeric material such as silicone or urethane which willminimize trauma to the vascular intima, as will be appreciated by one ofskill in the art. As a safety feature, to facilitate complete removal offragments of a broken guidewire, a safety wire may be secured at one endto the inside of the tip 20, and at the other end to the post 22 orsupport 24.

Disposed intermediate the tip 20 and body 11 of a flexible implement 10in accordance with the present invention is a floppy but controllablesteering region 16. Steering region 16 is constructed in a manner thatfacilitates lateral displacement of the tip 20 relative to the axis ofthe body 11, through physical design and/or choice of flexibleconstruction materials.

For example, in a typical angioplasty guidewire or catheter, where theflexible body 11 comprises a metal wire coil, the revolutions of wireper unit of axial distance along the body is reduced in the steeringregion 16 relative to body 11 to provide a looser wound coil havingspace 17 between adjacent wire loops, as illustrated in FIGS. 1-6. Thus,referring to FIG. 2, it can be seen that lateral deflection of steeringregion 16 to the left may involve both an axial compression of adjacentwire loops on the inside surface 36 of the bend, and an axial separationof the adjacent wire loops on the outside surface 38 of the bend.

Alternative designs or materials can be employed, provided that thecatheter exhibits sufficient lateral flexibility. In general, thesteering region 16 may be made from a variety of suitable metal orplastic coils or flexible sleeves. Materials opaque to X-rays, such asplatinum, gold, tungsten, tantalum or the like, may be advantageouslyincorporated therein, to act as a fluoroscopic marker to aid in precisepositioning of a balloon section of the catheter.

In accordance with the steering mechanism of the present invention, asteering post 22 is provided, extending in a generally axial directionwithin the steering region 16 of flexible body 11. Preferably, thesteering post 22 is disposed coaxially within the central lumen ofsteering region 16 when the steering region 16 and body 11 are linearlyaligned, such as when at rest. See FIG. 1. As will be described, thesteering post 22 is secured in the steering region 16 in a manner thatsubstantially prevents axial displacement thereof yet permits lateraldeflection of the axis of the steering post 22 away from the axis ofbody 11.

Post 22 preferably comprises a resilient shaft which may be molded orextruded from any of a variety of materials, such as nylon, and may havea cross-sectional dimension of from about 0.002 inches up to about 0.012inches for use in a typical steerable angioplasty guidewire embodiment.Alternatively, a variety of resilient or springy metals in the form ofwire can also be used to form post 22, such as phosphor bronze or otherresilient metal. In general, it is desirable to select a material whichwill permit some degree of bending and return to its original shape, andwill resist axial compression under the forces typically applied in theintended use of the steerable implement 10.

The length of steering post 22 will, of course, be dependant upon thelength of the steering region 16. In a typical steerable guidewire forangioplasty applications, the entire steering region 16 will be on theorder of from about 0.25 to about 1.0 inches long, and the steering post22 may be from one-third to two-thirds that length. Although steeringpost 22 may extend distally all the way to the distal tip 20 of thesteerable implement 10, it is preferred to limit the length to theproximal one-half or one-third of the axial length of steering region 16to minimize rigidity in the steering region 16 yet permit sufficientsteerability thereof.

For example, in a typical angioplasty guidewire the distal end 27 ofsteering post 22 will be spaced apart from the interior surface of tip20 by a distance of from about one-tenth to one-half an inch or more,thus permitting the steering region 16 of the catheter shaft to be asfloppy as desired. However, in an embodiment where the distal portion ofa fiber optics bundle or flexible tube for defining a working channeladditionally functions as the steering post 22, the post 22 will extendall the way to the distal tip 20 and be exposed to the outside by way ofan opening therethrough. See, for example, FIG. 4.

In a particularly preferred embodiment, steering post 22 is furtherprovided with a bead or enlarged region 26 to optimize transmission oflateral force from the steering post 22 to the wall of steering region16. For this purpose, bead 26 is most effectively located at or near thedistal end of steering post 22. Bead 26 may be formed by dipping orcoating techniques, or may be a preformed member having an openingtherein for sliding over the end of steering post 22. Alternatively,post 22 can be molded or milled to provide a bead 26 integrally formedthereon. Bead 26 is preferably substantially circular in a cross-sectionperpendicular to the axis of post 22, and the external diameter of thebead 26 is only slightly less than the interior diameter of the steeringregion 16 so that maximum lateral motion of the steering post 22 istransmitted to the steering region 16, but bead 26 also remains only inslidable contact with the interior surface thereof.

The proximal end 23 of the steering post 22 is mounted to or inpivotable contact with a radial support 24, in a manner which permitspivoting of the steering post 22 throughout a full 360° range of motionabout the axis of body 11 The post may also be molded or milled as anintegral part of disk 24. The support 24 comprises any means by whichthe deflection wires 28 are displaced radially outwardly from the axisof the tubular body 11, relative to their point of attachment to thesteering post 22, as will be discussed.

Referring to FIG. 1, the support 24 of the illustrated embodimentcomprises a circular disk 25 located within the tubular body 11 of thesteerable implement 10, preferably located near the distal end thereof.The disk 25 is axially secured within the tubular body 11 to provide astationary radial support for at least one deflection wire 28, andpivotable mount for steering post 22. Disk 25 may be attached, forexample, by friction fit between adjacent turns of coiled spring wire.Steering post 22 preferably is attached to or in contact with the disk25 in a manner which permits it to swivel from 90 degrees to close to 0degrees, relative to the lateral plane of disk 25.

The disk 25 may be made of stainless steel or any of a variety of othersuitable materials such as other metals or plastic polymers which willprovide a sufficiently axially rigid seat for the proximal end 23 ofsteering post 22. Disk 25 may be formed by stamping from sheet stock anddrilling, injection molding, or other techniques well known in the art.Preferably, a central depression or orifice is provided thereon, forproviding an axial seat for steering post 22. The diameter of disk 25can vary, however, it will typically be no greater than, but mayapproximate the outside diameter of the steerable implement 10.Diameters from about 0.14 to 0.050 inches may preferably be used in theconstruction of cardiac angioplasty catheters.

Lateral deflection of the steering post 22 away from the axis of body isaccomplished by proximal axial displacement of any of a plurality ofdeflection wires 28 extending proximally throughout the length offlexible body 11. Although only a single deflection wire 28 or twodeflection wires can be used, preferably three or four deflection wires28 are employed to provide a full 360° range of motion of the steeringregion 16 about the axis of the body 11, as will become apparent. Only asingle deflection wire 28 will be described in detail herein.

The distal end of deflection wire 28 is secured such as by adhesives tothe steering post 22 at the distal end thereof, or at a variety of otherlocations along the length of post 22. Typically, securing deflectionwire 28 closer to the proximal end 23 of post 22 will maximize thelateral force component generated by axial displacement of thedeflection wire 28, and for that reason, deflection wire 28 ispreferably secured to post 22 within the proximal half or one-third ofthe axial length of the post 22 extending distally of support 24. By"attached" or "secured" to the post and similar language herein, it isto be understood that the deflection wire 28 must be mechanically linkedto the post 22 but need not necessarily be directly secured thereto. Forexample, the deflection wire 28 could be secured to an annular flange orring surrounding the post or other structure which may be convenientfrom a manufacturing standpoint to provide a sufficiently secure linkageto accomplish the intended steering function. Alternatively, an eye onthe end of the deflection wire can surround the post 22 and rest againsta stop formed by a milled shoulder or adhesive, or other means ofattachment as will be apparent to one cf skill in the art.

The deflection wire 28 preferably extends radially outwardly from thepoint of attachment to the steering post 22 to the support 24. For thispurpose, the support 24 is preferably provided with a notch or orifice40 for each deflection wire 28 to extend through, said orifice 40 spacedradially outwardly from the axis of the tubular body 11 by a firstdistance. The distal end of each deflection wire 28 is secured to thesteering post 22 at a point radially displaced from the axis of thesteering post 22 by a second distance, and the first distance ispreferably greater than the second distance to maximize the lateralcomponent of force. The second distance preferably approaches zero;however, it will inherently include the radius of the steering post 22where the deflection wire 28 is secured intermediate the two endsthereof.

In the most preferred embodiment of the present invention, fourdeflection wires 28 are provided, each passing through an orifice 40 insupport 24 spaced at angles of approximately 90° apart from each otheralong the plane of the support 24. In a three deflection wireembodiment, as illustrated in FIG. 1, each orifice 40 is separated fromeach adjacent orifice by an angle of approximately 120°.

The deflection wires may be made of stainless steel, nylon or any othersuitable material which provides sufficient tensile strength andflexibility. The diameter of the lines can range from 0.001 to 0.005inches or more, and suitability of particular sizes or materials can bereadily determined by experimentation.

A control device 18 for steering the catheter is shown schematically inFIGS. 1-3. The control device 18 is preferably provided at its centerwith a pivotable mount 32 to permit it to be tipped throughout a full360° range of motion. In the illustrated embodiment, control comprises acircular plate 34 secured to proximal end 12 of flexible shaft 10 by wayof pivotable mount 32. Deflection wires 28 are spaced equally radiallyoutwardly from the pivotable center of the control device and at equalangular distances around the plate 34. Deflecting plate 34 from a planenormal to the axis of shaft 10 transmits force via one or moredeflection wires 28, a component of which is resolved into a lateralforce to deflect the catheter tip toward or away from the longitudinalaxis of catheter. Selective tipping of the deflection plate 34 resultsin rotation of the catheter tip to any desired orientation.

A variety of alternative control devices can be envisioned for use withthe steerable implement of the present invention. For example, a "joystick" type device comprising a single lever which can be displaced toany position throughout a nearly hemispherical range of motion might beused. As a further alternative, a portion of the proximal end 12 oftubular body 11 is enlarged to a cross-section of a half inch or largerto facilitate grip. The enlarged section is provided with a plurality ofaxially slidable switches, one corresponding to each deflection wire 28.Manipulation of the switches by the thumb or forefinger will obtain thedesired deflection of steering region 16. As will be appreciated by oneof skill in the art, any control device will preferably be provided witha stop to prevent bending of the post 22 or steering region 16 past itselastic limit.

A variety of factors impact the amount of the lateral force componentexerted on steering post 22 by axial, proximal displacement of any ofdeflection wires 28. For example, as orifice 40 is moved further in aradially outward direction, the lateral force component will increase.Lateral displacement of orifice 40, however, is constrained by themaximum diameter that the steerable implement can have for an intendedapplication.

Alternatively, shortening the axial distance from the support 24 to thepoint of attachment 42 of the deflection wire 28 to the steering post 22increases the angle between the axis of post 22 and deflection wire 28,thereby increasing the lateral component of force. For this reason,support 24 is typically within one or two inches, and preferably lessthan one inch, from the distal tip 20 of an angioplasty catheter orguidewire embodiment of the invention.

A further alternative is illustrated in FIG. 5. In this embodiment, afulcrum 44 is provided at a point intermediate the radial support 24 andpoint of attachment 42 for maintaining the deflection wire 28 concave ina radial inward direction. The fulcrum 44 may conveniently comprise asubstantially radially symmetrical member such as a sphere or toroid,which can also function to limit proximal axial movement of steeringpost 22 through a central opening in support 24. In this embodiment, thepoint of attachment of deflection wires 28 may be to the fulcrum 44instead of directly to the steering post 22.

In accordance with a further aspect of the present invention, there isprovided a steerable medical implement for use in percutaneoustransluminal laser angioplasty applications. Referring to FIG. 4, thereis disclosed an elongate flexible implement 45 comprising at its distalend a floppy steering region 46. As described with previous embodiments,enhanced flexibility may be imparted to steering region 46 by providingspacing 47 between adjacent loops of wound wire 48.

A radial support means 49 is disposed at the proximal end of steeringregion 46, which may comprise a circular plate 50 or other structure fordisplacing deflection wires 52 radially outwardly from the axis ofimplement 45.

A waveguide such as a fiber optic bundle 54 extends the entire length ofthe implement 45, for directing laser light from a source (notillustrated) disposed at the proximal end of the implement 45, to apoint of application within a coronary artery at the distal tip 56 ofthe implement 45. For this purpose, the optical pathway 54 extendsthroughout the length of steering region 46 and traverses tip 56 by wayof an opening 58 therein.

Each of the deflection wires 52 is secured at its distal end to thefiber optic bundle 54 at a point intermediate radial support 49 anddistal tip 56. Preferably, as has been previously described, the pointof attachment of deflection wires 52 to the fiber optic bundle 54 isless than half the distance and preferably is within one-third of thedistance between the radial support 49 and distal tip 56, in order tooptimize the lateral component of force.

Thus, utilizing a control device as previously described, a laserangioplasty catheter incorporating the present invention permits thecontrolled direction of a beam of light transmitted through fiber bundle54 at any desired point within a full 360° circle on a plane normal tothe axis of the implement 45.

As is well known in the fiber optics art, numerous functions can beaccomplished through a waveguide such as fiber bundle 54. For example,substantially parallel but discrete bundles of fiber optics can besecured adjacent one another within the fiber bundle 54 to permit aplurality of discrete light transmitting channels. Alternatively, aplurality of concentric optical pathways can be provided as is wellknown in the art.

A plurality of discrete optical pathways may advantageously be used toperform a variety of functions. For example, a first optical pathwaymight be utilized to permit visualization of the stenotic site or othersurface to be treated. A separate optical pathway may be utilized totransmit light for illuminating the site. Yet a third optical pathwaymight be utilized to transmit the laser light. These and other aspectsof the fiber optics and laser light source are well known to thoseskilled in the fiber optics art.

A variety of additional functions may be performed through use of theadditional interior space within the housing of steerable implement 45.For example, in a preferred embodiment, an aspiration duct may beprovided near the distal end of the implement 45, for suctioning debrisor gases which may be generated as a result of the action of the laser.Alternatively, in place of a waveguide 54, a flexible tube may beincorporated into the steering device of the present invention, therebyproviding a working channel to receive additional implementstherethrough.

Although this invention has been described in terms of certain preferredembodiments, other embodiments that are apparent to those of ordinaryskill in the art are also within the scope of this invention.Accordingly, the scope of the invention is intended to be defined onlyby reference to the appended claims.

I claim:
 1. A steerable guidewire for percutaneous transluminalinsertion into the coronary vascular system and controlled negotiationof branches and turns therein, comprising:an axially elongate flexiblehousing having distal and proximate ends, said distal end being providedwith a resilient tip; a flexible steering region displaced intermediatesaid distal and proximate ends of said housing; and at least onedeflection wire for causing lateral deflection of said steering regionupon axial displacement of said deflection wire along said housing. 2.The device of claim 1 wherein said steering region comprises a differentmaterial than the remainder of said body.
 3. The device of claim 1,wherein said body comprises a wound coil.
 4. The device of claim 3,wherein said coil has fewer revolutions per unit of axial distance alongsaid body in said steering region.
 5. The device of claim 1, whereinsaid body has a diameter less than 0.125 inches.
 6. The device of claim5, wherein said body has a diameter between 0.014 inches and 0.018inches.
 7. The device of claim 1, comprising at least three deflectionwires.
 8. A steering mechanism for a steerable guidewire having aflexible steering region, comprising:a steering post secured to saidsteering region in a manner that substantially prevents axialdisplacement thereof yet permits lateral deflection of the axis of saidsteering post away from the axis of said steerable guidewire; at leastone deflection wire secured to said steering post; and a control devicefor axially displacing said deflection wires so as to laterally displacesaid steering post and said steering region.
 9. The steering mechanismof claim 8, wherein said steering post has proximal and distal ends andwherein said deflection wire has proximal and distal ends and the distalend of said deflection wire is secured at a point intermediate saidproximal and distal ends of said steering post.
 10. The steeringmechanism of claim 8, wherein said control device comprises a pivotablymountable circular plate secured to said deflection wires.
 11. Thesteering mechanism of claim 8, wherein said control device comprises asingle lever secured to said deflection wires, said lever beingdisplaceable to any position throughout a nearly hemispherical range ofmotion.
 12. The steering mechanism of claim 8, wherein said controldevice is provided with a stop to prevent bending of said steering postor said guidewire beyond their elastic limits.
 13. A method of steeringa guidewire of the type having at least one deflection wire for steeringsaid guidewire and an elongate flexible shaft with a proximal and adistal end, said distal end being provided with a tip, through branchesand turns in the coronary vascular system, comprising:introducing saidguidewire into the coronary vascular system; advancing said guidewirethrough the coronary vascular system until a branch or a turn isencountered; steering said tip of said guidewire into said turn by axialdisplacement of said deflection wires and advancing said guidewirethrough said turn; straightening said guidewire by axial displacement ofsaid deflection wire; and further advancing said guidewire through thecoronary vascular system.
 14. The method of claim 13, wherein saidguidewire has more than one deflection wire and wherein thestraightening step comprises axial displacement of a differentdeflection wire than the deflection wire axially displaced in thesteering step.
 15. The method of claim 13, wherein said guidewire has atleast three deflection wires and wherein axial movement of any one ofsaid deflection wires in a proximal direction causes lateral deflectionof said tip and allows a full 360° range of motion about the axis ofsaid flexible shaft.
 16. A steerable guidewire, comprising:an elongateflexible housing having a diameter less than 0.125 inches and havingproximal and distal ends and a central lumen extending therebetween, thedistal end of said housing being flexible in a lateral direction; and atleast two deflection wires extending along the housing for causinglateral deflection of said distal end of said housing.
 17. A steerableguidewire as in claim 16, additionally comprising a resilient tip on thedistal end of said housing, said tip being movable between a firstposition on the axis of said housing and a second position displacedradially from the axis of said housing.
 18. A steerable guidewire as inclaim 16, wherein said housing has a diameter between 0.014 inches and0.018 inches.
 19. A steerable device for controlled negotiation throughbranches and turns, comprising:an axially elongate body having distaland proximal ends and a central lumen therebetween; a flexible steeringregion disposed intermediate said distal and proximal ends of said body;a deflecting means within said central lumen; and at least onedeflection wire secured to said deflecting means for causing deflectionof said steering region upon axial displacement of said deflection wire.20. A guidewire as in claim 19, wherein there are at least threedeflection wires so that through combinations of axial displacement ofsaid deflection wires, said steering region is caused to deflectlaterally and rotate throughout a full 360° range of motion about theaxis of said flexible shaft.
 21. A guidewire as in claim 19, whereinsaid deflecting means is a steering post.
 22. A guidewire as in claim19, additionally comprising a support for said deflecting means whereinsaid deflecting means is in pivotable contact with said support.